Catcher in the rye , Ban or not ban

The ALA has every reason to ban books innapropriate for children. But some books like harry potter and others that i read as a child are being challenged. Catcher in the rye is a great example. It has been challenged many times and has been banned for many years now. I can see why they banned that book back then becasue the man who shot john lenon was upsesseed with this book due to its violence. The main character says god damn alot. I think there should be an age limit on some of these banned books and that high school students should have the choice to choose what books they read and learn about.